7,806 research outputs found
Characterization of Si/Si_(1-y)C_y superlattices grown by surfactant assisted molecular beam epitaxy
Si/Si_(0.97)C_(0.03) superlattices grown on Si(001) substrates by Sb surfactant assisted molecular beam epitaxy are characterized by in situ reflection high energy electron diffraction (RHEED), atomic force microscopy, transmission electron microscopy (TEM), and high resolution x‐ray diffraction. The RHEED shows that, in the absence of Sb, the growth front roughens during Si_(0.97)C_(0.03) growth and smooths during subsequent Si growth. In contrast, when Sb is present, the growth front remains smooth throughout the growth. This observation is confirmed by cross‐sectional TEM, which reveals that for samples grown without the use of Sb, the Si/Si_(0.97)C_(0.03) interfaces (Si_(0.97)C_(0.03) on Si) are much more abrupt than the Si_(0.97)C_(0.03)/Si interfaces. In the case of Sb assisted growth, there is no observable difference in abruptness between the two types of interfaces. Atomic force microscopy micrographs of the Si_(0.97)C_(0.03) surface reveal features that could be the source of the roughness observed by RHEED and TEM
Sb-surfactant-mediated growth of Si/Si1–yCy superlattices by molecular-beam epitaxy
Si/Si0.97C0.03 superlattices were grown on Si(001) substrates by molecular beam epitaxy (MBE) to study the use of Sb as a surfactant during Si1–yCy growth. In situ reflection high energy electron diffraction (RHEED) shows that while carbon easily disrupts the two-dimensional growth of homoepitaxial Si, such disruption is suppressed for layers grown on Sb-terminated Si(001) surfaces. Cross-sectional transmission electron microscopy (TEM) reveals that for samples grown without the use of Sb, the Si/Si0.97C0.03 interfaces (Si0.97C0.03 on Si) were much more abrupt than Si0.97C0.03/Si interfaces. In the case of Sb-mediated growth, differences in abruptness between the two types of interfaces were not readily observable
Large Magnetoresistance in Co/Ni/Co Ferromagnetic Single Electron Transistors
We report on magnetotransport investigations of nano-scaled ferromagnetic
Co/Ni/Co single electron transistors. As a result of reduced size, the devices
exhibit single electron transistor characteristics at 4.2K. Magnetotransport
measurements carried out at 1.8K reveal tunneling magnetoresistance (TMR)
traces with negative coercive fields, which we interpret in terms of a
switching mechanism driven by the shape anisotropy of the central wire-like Ni
island. A large TMR of about 18% is observed within a finite source-drain bias
regime. The TMR decreases rapidly with increasing bias, which we tentatively
attribute to excitation of magnons in the central island.Comment: 12 pages (including 4 figures). Accepted for publishing on AP
Housing, Feeding and Management of Calves and Replacement Heifers in Swedish Dairy Herds
A questionnaire was sent to 1500 randomly selected dairy herds in Sweden, asking for general information about the herds, including routines from birth to first calving and also routines at breeding, calving and during the grazing period. Fifty-eight percent of the questionnaires were returned. The preweaned calves were kept in individual calf pens in 68% and in group housing systems in 28% of the herds. Pens with slatted floors were the main housing system for replacement heifers from weaning to breeding, and tie stalls from breeding to first calving. Whole milk was used in 44% and milk replacements in 42% of the herds. The calves received, as a median, 2.5 litres of milk per meal and 2 meals per day. The median age at weaning was 8 weeks. Age was the single most common criteria used for deciding both weaning and breeding time. The median age when the heifers were first turned out to pasture was 6 months. Prophylactic anthelmintic treatment was used by 65% of the herds. The most common diet for replacement heifers before calving was a combination of grain, hay and silage
First ice core records of NO3− stable isotopes from Lomonosovfonna, Svalbard
Samples from two ice cores drilled at Lomonosovfonna, Svalbard, covering the period 1957–2009, and 1650–1995, respectively, were analyzed for NO3− concentrations, and NO3− stable isotopes (δ15N and δ18O). Post-1950 δ15N has an average of (−6.9 ± 1.9) ‰, which is lower than the isotopic signal known for Summit, Greenland, but agrees with values observed in recent Svalbard snow and aerosol. Pre-1900 δ15N has an average of (4.2 ± 1.6) ‰ suggesting that natural sources, enriched in the 15 N-isotope, dominated before industrialization. The post-1950 δ18O average of (75.1 ± 4.1) ‰ agrees with data from low and polar latitudes, suggesting similar atmospheric NOy (NOy = NO + NO2 + HNO3) processing pathways. The combination of anthropogenic source δ15N and transport isotope effect was estimated as −29.1 ‰ for the last 60 years. This value is below the usual range of NOx (NOx = NO + NO2) anthropogenic sources which is likely the result of a transport isotope effect of –32 ‰. We suggest that the δ15N recorded at Lomonosovfonna is influenced mainly by fossil fuel combustion, soil emissions and forest fires; the first and second being responsible for the marked decrease in δ15N observed in the post-1950s record with soil emissions being associated to the decreasing trend in δ15N observed up to present time, and the third being responsible for the sharp increase of δ15N around 2000
Severe asphyxia due to delivery-related malpractice in Sweden 1990–2005
Aim
The objective of the thesis was to describe the most common causes of
substandard care during labour contributing to severe asphyxia or
neonatal death, to study risk factors related to asphyxia associated with
substandard care and to explore the occurrence of substandard care during
labour.
Background
There are about 100 000 infants born every year in Sweden. Most infants
are born healthy after uncomplicated deliveries. However, 20-50 claims
for financial compensation are made annually to the Patients Advisory
Committee (PA C) on suspicion that substandard care during labour has
contributed to severe asphyxia causing cerebral palsy or death. Even if
this group of patients is notably small, asphyxia causes life-long
impairment and immeasurable suffering to the patients and their families.
In addition, the insurance costs are substantial and amount to 25% of all
costs related to substandard care in Sweden. With the exception of this
group of patients, and claims to the Health Services Disciplinary Board,
the frequency of substandard care in relation to childbirth is fairly
unknown.
Material and methods
Inclusion criteria were pregnancies with a gestational length ≥ 33 weeks,
a spontaneous or induced start of labour, a normal CTG at admission for
labour, and Apgar score < 7 at 5 minutes of age (Papers I-IV). 472 case
records of deliveries from 1990-2005, filed at the PAC were scrutinised.
In Paper I and II the deliveries and acts of neonatal resuscitation
procedures are described. In Paper III, maternal characteristics, factors
related to care and infant characteristics for patients receiving
lifelong financial compensation from PAC are compared with all infants
with full Apgar score at 5 minutes of age born after a vaginal start
during the same time period in Sweden (n=1.141 059). In Paper IV
deliveries and risk factors from 313 infants with Apgar score < 7at 5
minutes of age, born in the Stockholm County are compared with 313
infants with full Apgar score at five minutes of age, matched for year of
birth.
Results
One-hundred and seventy-seven infants were considered to have been
severely asphyxiated due to substandard care during labour (Paper I-III).
The most common occurrences of malpractice in conjunction with labour
were neglecting to supervise fetal well-being (98%), neglecting signs of
fetal asphyxia (71%), including incautious use of oxytocin (71%) and
choosing a non-optimal mode of delivery (52%) (Paper I). Resuscitation of
the 177 severely asphyxiated infants was unsatisfactory in 47%. The most
important flaw was the defective compliance with the guidelines
concerning ventilation and prompt paging for skilled personnel in cases
of imminent asphyxia (Paper II). Risk factors associated with asphyxia
included maternal age ≥ 30 years, short maternal stature (< 159 cm),
previous caesarean delivery, insulin-dependent diabetes, induced
deliveries and night deliveries, where the increases in risk were doubled
to a four-fold. In addition, dystocia of labour was associated with a
five-fold increase in risk, which was further increased if epidural
anaesthesia or opioids were used. Small- and large-for-gestational age
infants, post-term (> 42 weeks) births, twins and breech deliveries had a
three to eight-fold increase in risk of asphyxia when there was
substandard care during labour (Paper III). Two thirds of infants born in
the Stockholm region 2004-2006, with Apgar score < 7 at 5 minutes but
also one third of the healthy controls were subjected to some kind of
substandard care during labour (Paper IV). The main causes of substandard
care during labour were related to misinterpretation of CTG, not acting
timely on abnormal CTG, and incautious use of oxytocin. The risk of
asphyxia increased with duration of abnormal CTG and was increased
fifteen-fold when this was abnormal for ≥ 90 minutes. Oxytocin was
provided without sign of inertia in 20% of cases and controls and the
risk of asphyxia was increased more than fivefold in cases of
tachysystole. Infants born after a spontaneous vaginal delivery with
abnormal CTG for more than 45 minutes had a more than sevenfold risk of
low Apgar score. In instrumental deliveries that were considered complex,
there was a more than seventeen-fold risk of an Apgar score < 7 at 5
minutes of age. Assuming that substandard care is causative for low Apgar
score, we estimate that 42% of the cases could be prevented by avoiding
substandard care (Paper IV).
Conclusion
It is possible to improve patient safety during labour by applying
educational efforts on fetal surveillance and increasing awareness of
risk factors associated with asphyxia. The main causes of substandard
care during labour are related to misinterpretation of CTG, not acting
timely on abnormal CTG, misinterpretation of guidelines and misuse of
oxytocin. Low Apgar score at 5 minutes of age can substantially, be
prevented by avoiding substandard care
The effect of experience of ramps at rear on the subsequent ability of layer pullets to negotiate a ramp transition
In commercial situations, laying hens must negotiate levels to reach resources such as food, water and litter. Providing ramps in aviary systems reduces collisions and resultant keel bone fractures in adults. We investigated whether providing ramps during rear improved the ability of birds to transition between levels.
Chicks were reared commercially in two flocks both of which provided access to raised structures from three weeks of age. One flock had no ramps, but the other flock was provided with additional access to two types of ramp (wooden ladders, and grids formed from commercial poultry slats placed at an angle). At 8 weeks of age, 64 birds (32 from each rearing condition) were transferred to an experimental facility. At 10 weeks of age, 32 pullets from each group were trained to run to a food reward. During testing at 12–14 weeks of age the pullets accessed the food reward by moving up or down a ramp. The pullets’ behaviours and time taken to complete the task were recorded. Ramp use over three days was also observed in a room replicating a small-scale single-tier system. Four groups of 16 birds aged 12–14 weeks were housed for three days and the number of transitions between the raised tier and litter were recorded.
For upward transitions, more ramp-reared birds than control birds succeeded in reaching the food reward for both ladder (52% vs 13%) and grid ramps (74% vs 42%). Birds from the ramp-reared group took significantly less time to complete an upwards transition (68.8s ± 49.3) than the control group (100s ± 37.6) (p = 0.001). In addition, the control group showed more behaviours indicative of hesitancy (moving away, head orientations, ground pecking and crouching) before transitioning, and signs of difficulty when making upward transitions (crouched walks, pauses, turning, returning and escape attempts). In the group housing observations, the ramp reared groups had almost double the number of transitions between the slats and litter on day one compared to the control group. This difference was reduced by day three.
In summary, this suggests there are positive effects of providing ramp experience during rear shown by any combination of bird mobility, strength or cognitive ability leading to an increase in apparent confidence in older pullets. It is not known whether these benefits persist through to the laying period, but no detrimental effects were noted so we suggest that ramps should be included from the early rearing period onwards
The impact of the physical environment for caregiving in ordinary housing: Experiences of staff in home- and health-care services
The strong driving forces for ageing in place demand sustainable solutions for the housing and care of older people and the health and safety of home- and health-care staff. The aim of the study was to elucidate staff experiences of providing home- and health-care to older people living in ordinary housing. This study was part of a larger project investigating the relation between home design and conditions for care in ordinary housing. The data were gathered through focus group interviews with staff in home- and health-care. Three main themes were found according to staff experiences of particular rooms’ sizes and proportions, spatial configurations, and aspects to consider when designing new housing. This study contributes important knowledge about essential features of the physical environment for staff providing home- and health-care for older people in their own homes and to aid the development of functionally sustainable housing to minimise injuries to staff
Синтез и антиинфекционное протективное действие β-циклогексилметил- и β-2-циклогексилэтилгликозидов мурамоилдипептида
Осуществлен синтез β-циклогексилметил- и β-2-циклогексилэтилгликозидов мурамоилдипептида. Исходные перацетилированные β-циклогексилалкилглюкозаминиды были получены оксазолиновым методом. Установлено, что β-циклогексилметил- и β-(2-циклогексилэтил)-МДП обладают высоким антиинфекционным протективным эффектом при поражении мышей летальной дозой Staphylococcus aureus.Здійснено синтез β-циклогексилметил- і β-2-циклогексилетил глікозиді в мурамоїлдипептиду. Вихідні перацетильовані (β-циклогексилалкілглюкозамініди були отримані за оксазоліновим методом. Встановлено, що β-циклогексилметил- і β-(2-циклогексилетил)-МДП володіють високим антиінфекційним протективним ефектом при поразці мишей летальною дозою Staphylococcus aureus.The synthesis of β-cyclohexylmethyl- and β-2-cyclohexylethylglycosides of muramyldipeptide has been carried out. The starting peracetates of β-cyclohexylalkylglucosaminides have been obtained by the oxazoline method. It been found that β-cyclohexylmethyl- and β-(2-cyclohexylethyl)-MDP have a high anti-infection protective effect against the lethal dose of Staphylococcus aureus in mice
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